title: Pseudolayering of Gd-DTPA in the urinary bladder.
abstract: When excreted gadolinium diethylenetriaminepentaacetic acid (DTPA) collects in the bladder of a supine patient during magnetic resonance (MR) imaging, a puzzling pattern of signal intensities is noted. A gradual change in urine signal intensity with progressive addition of Gd-DTPA does not occur; instead, three sharply defined "layers" are seen both on T1- and T2-weighted images within the urine-Gd-DTPA mixture. The physical basis for this triple-layering phenomenon was investigated. A bladder phantom was constructed to reproduce the phenomenon. T1 and T2 relaxivities of urine doped with varying concentrations of Gd-DTPA were measured in vitro; measured signal intensities corresponded closely to predicted intensities. Early urine concentrations of excreted Gd-DTPA may be relatively high (10-40 mmol/L), resulting in extremely short T1 and T2 values (less than 30 msec). These extremely short relaxation times cause an artifactual pseudolayering of signal within the urine-Gd-DTPA mixture.
authors.affiliation: Department of Radiology, Bowman Gray School of Medicine, Wake Forest University, Winston-Salem, NC 27103.
authors.forename: A D
authors.initials: AD
authors.lastname: Elster
authors.forename: W T
authors.initials: WT
authors.lastname: Sobol
authors.forename: W H
authors.initials: WH
authors.lastname: Hinson
mesh_terms: D003287:Contrast Media / Q000008:administration & dosage; D005682:Gadolinium / Q000008:administration & dosage / Q000652:urine*; D019786:Gadolinium DTPA; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D009682:Magnetic Resonance Spectroscopy / Q000295:instrumentation; D008961:Models, Structural; D009942:Organometallic Compounds / Q000008:administration & dosage; D004369:Pentetic Acid / Q000008:administration & dosage; D001743:Urinary Bladder / Q000473:pathology*
chemical_list: D003287:Contrast Media; D009942:Organometallic Compounds; D004369:Pentetic Acid; D005682:Gadolinium; D019786:Gadolinium DTPA